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GET THE INSIDE SCOOP ON REFERENCE: THE NATURAL CITY
SAM BENVIE SCHOOLS THE YOUTH
The underlying theme of ecological references was introduced to me 20 years ago when I was a student at Ryerson studying Landscape Design. Sam was growing 300 species from seed at the base of the architecture building. I remember him casually mentioning the cliff reference to me in passing. I specifically remember saying something snotty like “whats the practical application of the theory.” Yup. I have been literally thinking about how to apply this idea in my practice for 20 years. It was so nice to team up with Ryerson and have Sam as our host to explore practical applications of ecological references in planting design.
REFERENCE: THE NATURAL CITY TAKES FLIGHT
After more than a year of planning it all came down to a couple late nights of printing and collating packages. From the beginning the vision was Ecologists speaking to designers, landscape contractors, students and growers about specific ecosystems that are relevant to urban planting design in Toronto. We decided it was important to cover Alvars, Cliffs, Clay bluffs and Oak Savannahs. We also decided to reserve time in the afternoon for workshops so attendees could work through the nuts and bolts of using ecological references as a practical tool.
ECOLOGISTS PRESENT TO DESIGNERS AND TRADES
We had so many wonderful speakers to choose from and some who could not make it. Perhaps most notably, one of the authors of the Ecosites of Ontario document was not allowed to attend due to a travel restriction on government employees (thanks Doug). Rest assured dear reader we will be retrying next year! Our final list of speakers and bios:
STEFAN WEBER HAS A PLAN THAT BEGINS WITH SEEDS
I have already talked about the great work that St Williams is doing planting seed orchards. Stefan introduced the idea and talked about the Hamilton Seed Strategy he developed through Ontario Plant Restoration Alliance.
According to Weber seed orchards perform triple duty as pollinator gardens, seed production and green business. Another benefit is that it reduces impact on remnant populations in the wild while preserving source identified seed and genetic diversity.
Weber says that St. Williams has over 100 acres planted as seed orchards. Stefan has multiple projects on the go including working with the ministry of natural resources on establishing prairie grasslands on roadsides and is a founding member of the Ontario Plant Restoration Alliance (OPRA).
Another field at St. Williams was home to a patch of Quercus prinoides. I was having difficulty loading the photo but here is a photo showing the incredible variation in leaf colour from Mary Gartshore’s seed orchard.
Weber also showed us an example of Lupinus perenne, a regionally rare species that was reestablished in this field at Mary Gartshore’s farm. Weber advocates for using the tools of horticulture to leverage interventions and ramp up production.
STEFAN WEBERS SHARES LOCAL KNOWLEDGE OF CLAY BLUFFS WITH DESIGNERS AND TRADES
Weber recognized that novel urban habitats present an opportunity for using ecological references in planting design. The fact is that Weber has supported this approach the first time we discussed it. The last time Weber presented in Toronto to the trades, it came up in passing that there are lots of plants growing in the Clay Bluffs at 16 mile creek outside of Oakville. It made perfect sense to have him come back and get into more detail.
Weber introduced the site and mentioned that it is home to one of the largest populations of Mertensia virginica (Virginia Bluebells).
Photo by FritzFlohrReynolds
Weber showed us a good way to distinguish Acer nigrum from Acer saccharum is the fuzzy margin of the leaf. In autumn the fall colour is salmon! 16 Mile Creek is a good source of seed for Platanus occidentalis (American Sycamore), Anemone canadensis (Canada Anemone).
Photo by 阿橋花譜 KHQ Flower Guide
According to Weber its not worth collecting seed from Erythronium americanum (Trout Lily) since it takes 7 years to flower! St. Williams is working on Jeffersonia diphylla (Twin Leaf).
Photo by judygva
Weber noted that colonies of Andrena bees use Micranthes virginiensis (Early Saxifrage) as a food source in spring. Weber mentioned that Antenarria neglecta (Smooth Pussytoes) form lovely mats and they would love to grow Calystegia spithamaea (Upright Bindweed) at the nursery.
Photo by aarongunnar
Weber showed slides of several plants that thrive on the hanging prairies at the top of the bluff. Sysirinchium montanum (Blue Eyed Grass), Shephardia canadensis (Soapberry) his favourite Taenidia integerrima (Yellow Pimpernel).
Photo by Matt Lavin Shepherdia canadensis
Photo by wackybadger Taenidia integerrina
Rosa carolina (Carolina Rose) and Penstemon hirsutus (Hairy Beardtongue) grow on the edges of the bluff. During question period Terry Fahey asked about the improbable appearance of Hamammelis virginiana (Witchhazel) since it usually appears at a moist forest edge. Weber replied that Witchhazel is very adaptable and was happily growing on the very dry conditions at 16 mile Clay Bluff.
Photo by cricketsblog Rosa carolina
WE AREN’T WALMART!
Someone asks what species do you wish were currently available? Weber replied that there are too many to list. “We grew hundreds of prickly ash and we couldn’t give them away. Then years later someone wanted it. We aren’t Walmart”
WHAT THE %$&! IS NICHE PARTITIONING
My plan to just sit in the audience and tweet, soak in everything and be a student at our event worked! In answer to question regarding what drives relationships between plants, Weber responded “NICHE PARTITIONING!” So now I have something new to think about. The layers of complexity to this game boggles the mind.
WILL VAN HEMMESEN TELLS YOU EVERYTHING YOU NEED TO KNOW ABOUT SAVANNAHS
Next Hemmesen explains that Ontario’s prairies and savannahs are scattered around southern Ontario and occur on sandy soils. Most of these landscapes around Norfolk county are gone now Hemmesen laments. Historically grasslands were converted to agricultural land, the remnants that exist now were unsuitable for agriculture, along railroad right of ways and first nations reserves says Hemmesen. A savannah is basically a prairie with big trees. Hemmesen continued the prairies around here are tall grass prairies distinct from those that occur on the great plains. Hemmesen talked about the incredible root systems that can extend up to 5 metres down and how that can help control erosion.
PRAIRIE PLANTS PRESENT MIXED BAG OF SUITABILITY FOR URBAN CONDITIONS
Hemmesen described typical prairie species as tolerant of low pH. This is definitely a plus as we have lots of limestone based soils and most contractors use limestone based building materials for walkways, patios and walls. Hemmesen mentioned that prairies and savannahs are well know fire driven ecosystems. Without fire prairies and savannahs will generally succeed to thickets and forests. This presents a significant challenge in an urban area. According to Hemmesen in rural settings grazing can simulate fire to a certain extent but does not promote seed germination required for species to replenish populations over time. In an urban setting the equivalent disturbance regime to grazing would be maintenance and monitoring (weeding out trees). The following plant list was provided by Hemmesen.
Some species described by Hemmesen are rare occurring only in remnant prairies such as the Thames River Prairie home to Hypericum prolificum (Shrubby St. Johns Wort).
Photo by FritzFlohrReynolds Hypericum prolificum
Hemmesen shared that these rare ecosystems are very calcareous, perched fens that have unique plant assemblages. Another strength for use in urban environments are plants listed above are adapted to full sunlight, hot summers and variable moisture conditions. I suspect that this is in part a function of soil depth to accommodate deep root systems (a condition that may or may not be the case on a typical site in Toronto). Many prairie species are regionally rare and confined to the Ojibwe prairie and Walpole island. Hemmesen provided examples such as Silphium laciniatum (Compass Plant), Asclepias verticillata (Whorled Milkweed), Liatris spicata (Dense Blazing Star), Solidago speciosa (Showy Goldenrod) and Coresopsis triptera (Tall Tickseed).
*NATIVE PLANTS COLONIZE LOCAL GREEN ROOF
Desmodium canadense (Showy Tick Trefoil) appeared one day on the Mountain Equipment Coop green roof. At the time we were delighted that a native plant with a showy flower was living on a green roof that gets visited by hundreds of people every year. Within a couple summers it had multiplied and began to cover large portions of the green roof. It was decided to harvest the spent flowers prior to setting seed to help keep numbers under control.
Photo by wackybadger
MANY REGIONALLY RARE SPECIES ARE COMMONLY AVAILABLE AT NURSERIES
Hemmesen mentioned Missouri Ironweed and Culvers Root are regionally rare. These plants are available in the trade, however, they are not necessarily grown from source identified seed. Hemmesen pointed out that some restorations do not use plants native to Ontario. Strictly speaking Hemmesen views this type of work as creating novel habitats rather than traditional restoration. Hemmesen defines restoration as recreating an ecosystem where it historically occurred. In an urban setting historical references have mostly been cemented over by development. This came up a few days later in a conversation with Stephen Smith who mentioned there was remnant populations of prairie plants along the West Toronto Railpath when they did restoration work 7 years ago. I believe one of the species he mentioned was Spartina pectinata (Prairie Cordgrass).
Photo by cultivar413 Spartina pectinata
In general Hemmesen described a continuum between true restorations and on the other end prairie gardens that still provide beneficial habitat. During question period someone asked if there is an example where a restoration was actually bad? Hemmesen replied “no”. Another person questioned whether their was any point in doing restoration in an urban setting to which Hemmeson replied “the objective should not be to restore prairie but rather to control invasives and promote diversity of site”.
NEIL TURNBULL PUTS THEORY INTO PRACTICE
We were extremely honoured to hear from the only landscape architect speaker of the day. Neil Turnbull designed and installed the garden at the Gardiner Museum. Turnbull studied horticulture in Scotland and has been working in the field for 40 yrs. Turnbull told us that they loved his first sketch but they didn’t have any money “We did the job as a gift and it has been giving back ever since”.
According to Turnbull the idea for the crevice garden came from a botanical garden in Montreal. Turnbull added “There is a rhythm to the stonework anchored by the pines”. The best thing about these gardens is they are gravel and sand. These gardens are gardens inspired by talus slopes in Europe. Turnbull revealed how plants got established blowing in from the neighboring green roof at the trial garden at the farm.
Turnbull also mentioned that he was a fan of Douglas Tallamy. Stating “if nothing is eating the leaves of your plants then its not contributing anything to habitat. The hackberry I had was a monster completely covered in galls”
Pachyscilla celtidismamma (Hackberry Nipplegall Maker)
MEMORABLE TURNBULL QUOTES
“I really like what you can grow in gravel and sand, Baptisia for example”
“The layers of stone create all these different habitats. some of these areas do get weedy but elfin thyme is tough as concrete and no weeds will grow in it.”
“People loved it so much we had to put a sign to keep people from climbing all over it.”
ALBERT GARAFALO BREAKS DOWN ALVARS
Albert Garafalo started off saying Alvars are native equivalent of rock gardens and green roofs. (BOOM!) Garafalo stated bedrock influenced vegetation often good for horticultural purposes (another BOOM!) Garafalo mentions development as a good example (Peter Del Tredici likens development to glaciation more on that at Reference 2020!).
Plants that thrive in Alvars must endure flooding, shallow soil, frost heaving, lack of nutrients and variable moisture said Garafalo.
CHUBBY ALVAR PLANTS WITH BIG UPSIDE
Pellaea atropurpurea (Purple Cliff Break)
Asplenium Viride (Green Spleenwort)
ALVAR SOILS ARE A REFERENCE FOR GREEN ROOFS AND WALLS
Plants occuring in cliffs, talus slopes and crevices formed from falling rock can have rich soils that accumulate over time (note anybody who knows more about this reach out). Typically Alvars have minimal soil and face extreme temperatures from heating of the bedrock. Moisture regimes in the soil range from fully saturated to completely dry Garafalo said.
COMMON PLANTS HAVE SECRET SUPER POWERS
According to Garafalo alvars occur all over the world but only represent a tiny fraction of ecosystems worldwide. Many species living in alvars are endemic and are common horticultural plants (although these are familiar plants to me, many of them I did not know had the capacity to grow in these conditions). Here are some examples of common horticultural plants that also grow in alvars.
Juniperus horizontalis and Juniperus virginiana
Potentilla recta (Rough fruited cinquefoil)
Rhus aromatica (Fragrant sumac)
COMMON HORTICULTURAL PLANTS OF ALVAR GRASSLANDS
(we might think of alvars as pavements but alvar grasslands are a thing).
Deschampsia cespitosa (Tufted hair grass) couldn’t find a photo with proper attribution, then I saw this one from Maui loved the name and where its growing. Enjoy.
Sisyrinchium montanum (Blue Eyed Grass)
Danthonia spicata Poverty Oat Grass
COMMON HORTICULTURAL TREES GROWING IN ALVARS
(not everyone thinks of trees growing in alvars but that is totally a thing too)
Thuja occidentalis (White Cedar)
Quercus muehlenbergii (Chinquapin Oak) ok not common but totally awesome and have been used as street trees in Toronto!
Quercus macrocarpa (Bur Oak)
Hawthornes are mentioned in the literature on alvars but I couldn’t find a photo of Crataegus dilatata with proper attribution, so I settled for
Crataegus chrysocarpa (Fireberry Hawthorn).
Physocarpus opulifolius (Common Ninebark)
ECOLOGICAL LAND CLASSIFICATION IS GREAT TOOL FOR PLANTING DESIGN
Garafalo mentioned the Ecological Land Classification can be used to reverse engineer appropriate plants (which is exactly how we spent the afternoon).
DOUG LARSON SOUNDS OFF ON THE URBAN CLIFF HYPOTHESIS
Last speaker of the day was Doug Larson retired professor known for discovering old growth cedars living on Escarpment Cliffs. His talk was so dynamic I am going to share the full recording with you.
QUOTES OF THE DAY FROM DOUG LARSON
“Cities are not LIKE cliffs and alvars, they ARE cliffs and alvars!”
“Since humans evolved in a rock outcrop habitat cities are a REcreation”
“Dandelions come from highly disturbed scree slope environment”
“Cliffs represent 50% of plants and animals commonly found in the urban environment but make up a tiny percentage of total landmass on earth.”
SAM BENVIE TALKS ECOLOGICAL REFERENCES
Next up we had Sam Benvie talking about urban settings and asking what ecosystems do they reference.
We use this reference for disconnected downspouts:
Photo by lgke
STREETS ARE CANYONS
Photo by VV Nincic
Photo by eugene_o
BUILDINGS ARE CLIFFS:
Photo by wackybadger
Same perspective but in an urban setting low rise multi unit apartment building standing in nicely for limestone outcrop pictured above.
TYPICAL BUILDING BUILT AS “BONES WITH NO SKIN”
Photo by edkohler
What are the opportunities on terraces, balconies and exterior walls to achieve something that looks more like this? Is there a future where buildings don’t just keep heat in and rain out? In 2020 lets demand that building facades produce oxygen, sequester carbon and provide habitat!Photo by BLMOregon
Photo by cm195902
RUBBER HITS THE ROAD IN AFTERNOON WORKSHOPS
The afternoon was spent applying the concept of ecological references by working through four case studies from around Toronto.
After reading the description groups were asked to answer questions about the site and place the site on custom matrix (Michela Sutter and Sam Benvie worked really hard on this!)
After selecting for soil type and moisture regime the groups selected a vegetation type and matched it with one of 41 ecosites we preselected from the Ecological Land Classification document.
Each ecosite lists dominant species including woodies and herbaceous perennials. The list can be used as a starting point especially in the (common) case where no remnant ecosystem exists to be inventoried. For example rooftop gardens, terraces, balconies and new builds.
If you want to, check out those 41 Ecosites relevant to Toronto.
Well that wraps up the mega post refresher of what happened at Reference 2019. Looking forward to 2020!